I have tons of bookmarks. Pro-tip: make a bookmark, edit the bookmark, set the title to "" <empty string>. Then you have it's favicon as your site launcher.
sometimes I make use of the features "open all bookmarks in this folder".
other times I use the bookmark to (as somebody else mentioned already) weight consideration of sites I'm interested in getting results from.
aside: at hackreactor, I worked with some folks on the beginnings of a chrome extension to grab your bookmarks, analyze the content of each site, and suggest new bookmarks when you open a new tab. the suggestions part was working already by the time I came around. then I got a job and that pretty much fell out of priority... heh.